In a known conveyor belt, multiple modular links made of synthetic-resin are interconnected to one another by connecting pins along a longitudinal defined by the length of the conveyor belt and by the direction of its travel. Each of the modular links includes a plurality of boss sections at its leading and trailing edges, each boss section having an insertion hole adapted to receive a connecting pin. The boss sections are provided on the leading and trailing ends of the modular link in a staggered pattern.
Examples of known conveyor belts are described in Japanese patent publication No. 2004-262600, published Sep. 24, 2004, and in U.S. Pat. No. 8,371,437, granted on Feb. 12, 2013.
The conveyor belt of Japanese patent publication No. 2004-262600 can incorporate a tab attachment as shown in FIG. 6, configured to prevent uplifting of the belt, i.e., upward movement of the article-conveying surface of the belt, due to tensile force in a concavely curved zone of the travel of the belt. Uplift prevention is provided by bringing a guide-engaging section of the tab attachment into engagement with an uplift-preventing guide rail extending along a part of the path of circulation of the belt.
FIG. 6 is a side view of the tab attachment in a conventional conveyor belt 500. As shown in FIG. 6, the tab attachment 510 includes forward and rearward pin holes, each adapted to receive a connecting pin, and an engaging section 512, closer than the pin holes 511 to the inside of the loop formed by the belt.
A modular link of the conveyor belt is machined to remove boss-sections, and the tab attachment is inserted so that its pin holes 511 are at the positions previously occupied by pin holes of the modular link. Connecting pins are then inserted through the pin holes of the modular link and through pin holes 511 of the tab attachment.
In the conveyor belt having the configuration described in Japanese Unexamined Patent Application Publication No. 2007-537113, a guide-engaging section is an integral part of a modular link that extends across the full width of the belt.
A drawback of the conveyor belt 500 having the tab attachment shown in FIG. 6 is that the front and rear pin holes 511 of the tab attachment are connected to each other by a V-shaped connection instead of a connection extending linearly from one of the pin holes 511 to the other. Because the V-shaped connecting structure replaces a direct connection, the V-shaped connecting structure can decrease the overall tensile strength of the conveyor belt.
Another drawback is that, in those cases in which the boss sections of the modular link are arranged in a staggered pattern, that is the boss sections that extend in the direction of belt travel are offset widthwise from the boss sections that extend in the opposite direction, the pin holes 511 of the tab attachment will necessarily be offset from each other in the widthwise direction, causing the tab attachment to have an asymmetric shape so that tensile forces applied to the tab attachment tend to twist and deform the tab attachment.
In the conveyor belt of U.S. Pat. No. 8,371,437, the guide-engaging sections are fixed to a specific portion of a modular link that extends across the full width of the belt. Accordingly, different modular links are required to accommodate different desired positions of the guide-engaging part in the direction of the width of the belt.
This invention addresses the above-mentioned problems by providing a conveyor belt having uplift-preventing engagement portions that maintain the tensile strength of belt, avoid deformation, and are easily incorporated into a modular at any desired widthwise position and in any desired combination.